The present invention relates to nickel-based superalloys.
A typical prior art alloy is described in U.S. Pat. No. 3,160,500, issued to Eiselstein. It discloses nickel-chromium base alloys which have a good combination of mechanical properties over a wide range of temperature. Specifically, the aforesaid patent discloses a nickel-based alloy having a weight percent composition of about 55-62 nickel, 7-11 molybdenum, 3-4.5 columbium, 20-24 chromium, up to 8 tungsten, not more than 0.1 carbon, up to 0.05 silicon, up to 0.05 manganese, up to 0.015 boron, not more than 0.4 of aluminum and titanium, and the balance essentially iron, with the iron content not exceeding about 20% of the alloy. Inconel 625 is a commercial embodiment of the above Eiselstein patent.
The alloy described in U.S. Pat. No. 3,046,108, also issued to Eiselstein, has a nominal composition of about 53 nickel, 19 chromium, 3 molybdenum, 5 niobium, 0.2 silicon, 0.2 manganese, 0.9 titanium, 0.45 aluminum, 0.04 carbon and the balance essentially iron. These Eiselstein patents are similar in some respects, but the second teaches, for example, much lower molybdenum.
While the mechanical properties at high temperatures of alloys such as those described above are suitable for many purposes, such alloys are generally difficult to weld and, tend to swell when subjected to nuclear radiation.